1. Field of the Invention
The present invention relates in general to storage networks, and more particularly to methods, computer systems, and computer program products for managing storage networks to reduce power consumption.
2. Description of the Related Art
Modern storage networks (or Storage Area Networks (SAN)), typically include multiple “initiator” devices (e.g., hosts) and “target” devices (e.g., storage devices) interconnected through a storage interface, such as a Serial Attached SCSI (SAS) storage interface.
A SAS network (or SAS domain) also includes one or more SAS expander device which function as a switch and performs routing of a SAS frame from an initiator to a target. The SAS expander performs a SAS discovery process at initialization to obtain various information, such as the SAS addresses, device types (initiator, target, and expander), and supported protocols of all devices in the SAS domain and the identity of the SAS expanders to which all devices in the SAS domain are physically connected and position information indicating to which physical connection (PHY) of the SAS expanders the devices are connected. The SAS expander also generates a routing table on the basis of the above information and uses it for the routing of the SAS frame.
Moreover, the SAS supports a zoning function for controlling an access between devices. This function is used to assign zone identifications to SAS devices and to set which zones are allowed to access each other. Normally, one or more hosts are defined for a zone, one or more storages are defined for another zone, and the accessibility of the zones is defined for operation. Zoning is a function essential to many users for security.
A significant issue in storage networks, including SAS networks, is that of the power consumption of the various devices within the networks. One of the reasons managing the power consumption is difficult is that conventional networks do not include the functionality to determine which devices within the network are accessing other devices or being accessed from other devices.